The genus Impatiens is comprised of about 500 species of annual or perennial herbs or subshrubs. They are widely distributed particularly in the tropics and subtropics of Asia and Africa (Hortus Third A Concise Dictionary of Plants Cultivated in the United States and Canada, MacMillan Publishing Company (1976)).
A species of particular commercial interest is Impatiens Hawkeri, commonly referred to as New Guinea impatiens. New Guinea impatiens have foliage and floral characteristics that are desirable for bedding and pot-plant use. Impatiens plants reported to be native to New Guinea were classified in 1886 as Impatiens Hawkeri (New Guinea Impatiens, A Ball Guide, edited by W. Banner and M. Klopmeyer, Ball Publishing (1995)). Occasionally, these early specimens were referred to as Impatiens herzogii. Id. In the early 1900's, botanists from Germany, England and the Netherlands explored parts of the Sundra Islands, and by 1915, nine New Guinea impatiens species were identified from this area: I. dahlii, I. herzogii, I. laxterbachii, I. linearifolia, I. mooreana, I. polyphylla, I. rodatzii, I. schlechteri, and I. trichura. Id. Taxonomically, the collections were confusing and were considered to be habitat variations of I. herzogii rather than new species by Von R. Schlecter. Id. In the most recent taxonomic classification, Grey-Wilson proposed that New Guinea impatiens belong to one highly variable species, I. Hawkeri, in which 15 groups were identified based on geographic location. Id.
Although diverse phenotypically, typically members of New Guinea impatiens are fertile when crossed with each other or when selfed and generally have a 2n chromosome number of 32 (T. Arisumi, J. Hered., 64:77-79 (1973)). Breeding programs initiated in the early 1970's have led to the development of New Guinea impatiens cultivars that are adapted to a variety of light conditions, and have large flowers of a wide variety of colors including white, pink, red, orange, as well as biocolors (New Guinea Impatiens, A Ball Guide, edited by W. Banner and M. Klopmeyer, Ball Publishing (1995)). Foliage types include slightly rounded to lanceolate with smooth to serrated edges having colors ranging from green to burgundy and variegated. Id. Plant habits are typically mounded to spreading (Plant U.S. Pat. No. 5,921; Plant U.S. Pat. No. 4720; Plant U.S. Pat. No. 10,858). One cultivar ‘Radiance’ is described as having stems that are “slightly trailing” (Plant U.S. Pat. No. 7,098).
Interspecific crosses using Impatiens platypetala and Impatiens aurantiaca, two species closely related to Impatiens Hawkeri, have been used in New Guinea impatiens cultivar improvement, but offspring of these crosses are often sterile (New Guinea Impatiens, A Ball Guide, edited by W. Banner and M. Klopmeyer, Ball Publishing (1995)). Arisumi has successfully used ovule culture to recover interspecific hybrids of New Guinea impatiens, I. Hawkeri, crossed with I. auricoma, I. niamniamensis, I. uguenensis, and I. Wallerana (I. sultani in his publication) (T. Arisumi, J. Amer. Soc. Hort. Sci. 112(6): 1026-1031 (1987)).
Impatiens flaccida alba, a species noted for drought tolerance, has been used in interspecific crosses. Using ovule culture, hybrid seedlings were recovered from interspecific crosses of I. flaccida alba x I. repens and I. uguenensis x I. flaccida alba; however, no seedlings were recovered from crosses of I. flaccida alba x I. herzogii, I. flaccida alba x I. epiphytica, or I. flaccida alba x I. hookeriana (T. Arisumi, J. Amer. Soc. Hort. Sci. 105(5):629-631 (1980)). An additional study confirmed the previously reported I. flaccida alba x I. repens and I. uguenesis x I. flaccida alba successes, while no seedlings were recovered from a cross between I. flaccida alba x ‘Pele’ (A New Guinea impatiens cultivar) (T. Arisumi, J. Amer. Soc. Hort. Sci. 110(2):273-276 (1985)). Interspecific hybrids were also recovered from a cross between I. flaccida x I. Wallerana ‘Elfin White’ (I. sultani in his publication) (T. Arisumi, J. Amer. Soc. Hort. Sci. 112(6):1026-1031 (1987)).